1. Field of the Invention
The present invention relates generally to a vehicle-mounted drilling rig for wells and the like, and more particularly to a pipe storage and handling system for storing and manipulating drill pipes.
2. Description of the Prior Art
Mobile drilling rigs are well known and widely used in the drilling industry. Typically, mobile drilling rigs utilize a drilling mast or derrick adapted to be positioned in a generally horizontal position to facilitate transportation of the drilling rig from one location to another, and to be raised to a vertical, upright position to permit drilling. The drill rods or pipes used in the drilling operation are generally quite heavy and typically have a length up to 20'. The size and weight of the drill pipes usually inhibit manual handling. Thus, some type of mechanical means is typically provided to individually orient and position each drill pipe prior to being connected to a drill pipe string, and after the drilling operation is complete, to disconnect each drill pipe from the string and reposition the drill pipes back to their stored position. Moreover, it is desirable that the handling of the drill pipes be performed rapidly in order to reduce the costs associated with labor and fuel, and to obtain a high rate of usage of the drilling rig, which is usually quite expensive. It is also of concern that the handling of the drilling pipes be performed safely in order to avoid serious injury to the operator of the drilling rig.
Prior drilling rigs have utilized various mechanical means for handling and storing the drill pipes. Some drilling rigs include a derrick-mounted boom, or another similar mechanical device, to individually position each drill pipe in a vertical orientation adjacent the derrick for connection to the drill head, and after the drilling operation is complete, to individually remove each drill pipe and transport the pipe back to a storage location on the drilling rig. However, use of such a method to position and orient individual drill pipes typically relies on a considerable amount of manipulation and control by the operator, thus resulting in an increased likelihood of mishandling the drill pipes and correspondingly increasing the possibility of operator injury.
Other prior drilling rigs have attempted to incorporate automated or semi-automated mechanical devices to avoid, or at least minimize, the mishandling of the drill pipes by the operator. In some cases, a rotary magazine or carousel is mounted to the derrick and supported about a vertical rotational axis. The drill head is positioned above the carousel and forms a threaded connection with one drill pipe, and after the drill pipe is used in the drilling operation, the carousel is indexed or rotated about its rotational axis to place another drill pipe into position for subsequent connection to the drill head. Although the use of such automated or semi-automated devices may reduce manipulation and control by the operator, the carousel is only capable of holding a limited supply of drill pipes, typically no more than 7 or 8. After the drill pipes in the carousel are depleted, additional drill pipes must be individually transported from a pipe storage location on the bed of the drilling rig or from another transport vehicle. Typically, it takes too much time to reload the carousel, so any additional drill pipes that are required for completion of the drilling operation must be individually picked from a storage location by a crane or derrick-mounted boom and individually manipulated by the operator to a vertical orientation beneath the drill head.
Thus, carousel-type drilling rigs are presented with some of the same drawbacks and disadvantages associated with conventional drilling rigs when the drilling depth of the well exceeds a certain distance. For instance, in the water well drilling industry, well depths of up to 500' are sometimes required. Because rotary carousels are capable of storing, at most, 140' to 160' of drill pipe length, for wells requiring greater depths, additional drill pipes must be individually manipulated into position by the operator. Moreover, carousel-type drilling rigs have often been expensive, excessively complicated, and subject to costly breakdowns, particularly under severe drilling conditions. Furthermore, a rotary carousel is typically pre-loaded with drill pipes prior to departing for the drill site. The weight of the rotary carousel and the drill pipes contained therein results in a significant shift in the center of gravity of the mobile drilling unit, possibly resulting in decreased vehicle stability during transportation to the drill site. Additionally, due to the increased weight and higher center of gravity of the derrick, when the derrick is placed in its vertical drilling position, the overall stability of the drilling rig is substantially reduced during the drilling operation.
The present invention attempts to remedy at least some of the drawbacks and disadvantages associated with prior drilling rigs by providing a novel and unobvious pipe storage and handling system.